Sea Urchins are approximately 2"-3" in diameter, with the spines extending possibly twice that distance. Care must be taken to prevent the Urchins from accidentally overturning rocks in the reef tank causing damage to themselves and other reef inhabitants such as live corals.


Sea Stars characteristically have five arms extending from a central disk like a star. In the aquarium they can be fed small pieces of fish, placing the food near or even under the Sea Star.


Sponges filter massive amounts of water every day, feeding on the microplankton. Many will develop calcium, silica or sponging structures to support their shape. Sponges need to be anchored in rockwork; they do not tolerate sandy anchoring substrates.


Snails belong to one of the largest classes of organisms, with over 40,000 recognized species. While the shell itself is the primary means of protection, the snail's ability to adhere to a surface and its production of noxious compounds also discourages predators.


Shrimp make interesting and colorful additions to an invertebrate or reef aquarium. Shrimp are scavengers that will eagerly accept small pieces of fish or shrimp in the home aquarium. Shrimp have a hard outer shell (carapace) that must be shed (molted) for the shrimp to grow.

Sea Slug

Sea Slugs, sometimes called Nudibranchs, display vivid colors and an unusual body shape. Typically found in tropical reefs, their most notable characteristic is the pair of stalked rhinophores or horns at the head of the Slug.


Found in most marine environments, Lobsters inhabit the sandy bottom or the crevasses of rocky formations. Generally these animals are nocturnal, feeding at night, but most adapt well to the aquarium lighting.

Fan Worms

Fan Worms are marine segmented worms that are sessile, attached to rocks or sand by their base. The plume of Fan Worms can measure up to 10" in diameter on some species. Fan Worms require excellent water quality. Fan Worms require supplemental feeding with infusoria or foods designed for filter-feeding invertebrates.


Sea Cucumbers are best kept in reef or invertebrate aquariums. Water quality must be maintained at the highest levels, and care must be taken with any water intakes/overflows to ensure that the Sea Cucumber cannot become attached.


Found in nearly all marine environments, Crabs can range from less than an inch to over 12 inches in diameter. Crabs are scavengers of any type of edible matter they find, providing an invaluable "cleaner" function.